The present invention relates to imaging of biological tissue and, in particular, it concerns systems and methods for low-dosage imaging in babies or small animals.
It is known that a significant proportion of babies, primarily female, are born with a hip-joint defect known as a congenital dysplasia of the hip, abbreviated to "CDH". Estimates of the incidence of this condition vary between 1 and 15 per 1000 live births. Identification of this defect within the first few days of life is highly advantageous, allowing immediate and straightforward corrective action which typically results in completely recovery towards normal development of the hip. Delay in treatment, on the other hand, allows contracture of parts of the soft tissue surrounding the hip-joint, resulting in displacement or irreversible malformation of the hip, complicating the treatment and causing progressive hip problems later in life.
Although clinical neonatal procedures include various manipulations intended to detect CDH, these are not sufficiently reliably. It has been suggested to supplement the physical examination by additionally screening using ultrasound imaging techniques. However, ultrasound imaging can only be performed and the results properly evaluated by specially trained personnel, thereby limiting its usefulness for mass screening.
X-ray imaging has been used as a diagnostic tool for many years. Because of the possible harmful effects of high dosages of X-rays, use of X-ray imaging for very young children is conventionally kept to a minimum. Furthermore, conventional X-ray techniques only have diagnostic value after the age of about three months since, until that time, most of the tissue is cartilaginous and is substantially transparent to X-rays.
U.S. Pat. No. 4,852,137 to Mackay, U.S. Pat. No. 5,150,394 to Karellas and U.S. Pat. No. 5,187,730 to Fujihara relate to X-ray-based imaging systems in which the X-rays transmitted through the object of interest fall on a layer of phosphorescent material which acts as a secondary source, converting the pattern of incident X-ray radiation into light. The pattern can then be measured by use of a charge-coupled-device (CCD) to generate an image. This arrangement allows a considerable reduction of intensity of the X-ray radiation used compared to that required for conventional film exposures. The above-referenced U.S. patents are hereby incorporated in their entirety by reference as if fully set out herein.
There is therefore a need for a simple, reliable and cost effective method for screening newborn babies or small animals to identify malformed hips. It would also be advantageous to have a low-dosage X-ray-based system which may be used as a safe diagnostic tool for a wider range of applications involving newborn babies or small animals.